As the population is aging, response to lifestyle-related diseases of adults is becoming a large public problem. Especially, as to diseases related to high blood pressure, it is recognized that collecting blood pressure data for a long term is very important. From this viewpoint, various measurement apparatuses for measuring living body information such as the blood pressure are being developed. Among such apparatuses, a portable patient monitoring apparatus is proposed in which an ear is selected as a wearing position where daily living and behavior are not disturbed, that is, the patient monitoring apparatus is inserted into an external auditory meatus or other part of the external ear so as to be worn continuously (refer to patent document 1, for example).
This apparatus calculates blood pressure, and pulse, pulse wave, electrocardiogram, body temperature, arterial oxygen saturation and the like based on a received light amount of scattered light of infrared light or visible light that is radiated into the living body. Since various living body data can be measured only by wearing the apparatus by inserting it into the external auditory meatus, the apparatus is considered to be one that can automatically monitor physical status of the patient practically without restricting flexibility of physical activity of the patient.
Living body information measurement for pulse, pulse wave, arterial oxygen saturation and the like can be relatively easily realized using a photoelectric sensor and an electric circuit since it is only necessary to measure a pulse wave signal of a blood vessel part or an absorption spectrum of blood. On the other hand, for measuring blood pressure, since it is necessary to ascertain pulse wave that changes while increasing or decreasing a pressure applied to a measured part of a living body, it is generally necessary to provide a blood-pressure measurement apparatus with a cuff for increasing or decreasing a pressure onto the measured part and an air system that includes a pump and a valve for supplying and discharging air in the cuff.
In addition, among blood pressure measurement apparatuses, there is a blood pressure measurement apparatus (A&D company, TM2431, for example) that measures and records blood pressure on an upper arm 24 hours in a row. The blood pressure measurement apparatus is used as a means and the like for determining what sort of hypotensive drug should be taken in what way for obtaining most effective treatment.                [Patent document 1] Japanese Laid-Open Patent Application No. 9-122083        